I have been told that getting an FAA field approval is a lot like getting an elephant pregnant. 1. It's harder work than anyone would imagine, 2. It's accomplished by a lot of screaming and yelling, 3. Both parties are not sure of what the other is doing, and 4. It takes 19 months before you see any results. Well, this tongue-in-cheek metaphor may not be a 100 percent right, but it is not a 100 percent wrong either. Let's examine the policy behind field approvals and hopefully shine a little light on this murky subject.
What is a field approval?
A field approval is the granting by an FAA airworthiness safety inspector of an FAA approval for a major repair or major alteration based on examination of data or physical inspection or testing. There are three kinds of field approvals for which the local FAA inspector can sign off in Block 3 of the FAA Form 337. They are:
Examination of Data only: This is the most common form of field approval. The mechanic and repairman submit "acceptable" data to the local FAA office for approval. Once the data is approved in Block 3, the mechanic can make the major repair or alteration and have it signed off by an IA, repair station, or air carrier. Many mechanics make the mistake that once this data is field approved, it can be used over and over again to make another identical major repair or major alteration. This is not so! This field approval based on "Examination of Data only" is only for the aircraft identified in Block 1 of the FAA Form 337. However, if you want to do the exact same repair or alteration to another like make or model aircraft, you can use the original FAA Form 337 as the basis (acceptable data) for obtaining a new field approval for the second aircraft.
Physical Inspection, demonstration or testing of the repair or alteration: This is not done very often, but it does come in handy when a mechanic finds the wrong engine in the aircraft or when an auto pilot is on the aircraft and operating for several years but there is no paperwork. Since the aircraft has flown successfully for many hours, an FAA inspector can, if satisfied with the installation, approve the installation. The inspector would then sign Block 3 of a new FAA Form 337 that describes the engine or component and its installation.
Examination of data only for duplication on identical make and model aircraft by the original modifier: This is a procedure that saves the mechanic and the FAA a lot of time. For example, if a mechanic wants to install duplicate GPS on a Cessna 152 or vacuum storage containers for Jalapeno peppers on a Beech 18, he can do it with just one field approval. All the mechanic has to do is submit the acceptable data for the alteration or repair and ask the FAA inspector to sign Block 3 of the FAA Form 337 along with the statement that approves duplication of this repair/alteration on identical make and model aircraft by the original modifier. How does this work?
When the technician finishes a duplicate alteration on the next aircraft, he sends the FAA a regular FAA Form 337 properly identifying the second aircraft and identifying the approved data (date/aircraft) obtained under field approval on Block 8 of the Form 337. To avoid a phone call from the Flight Standards District Office (FSDO), I would recommend that you attach a duplicate copy of the original Field Approval Form 337.
One must understand that this field approval for duplication is not a property right like an STC is. The original modifier cannot "sell" the field approval to another party or "rent out" the data to another person.
Why do you need a field approval?
The question should be, why do you need approved data? In order to perform a major repair or a major alteration, four regulations require that you do the work in accordance with approved data. The regulations are FAR sections 65.95, 121.378, 135.437, and 145.51.
On May 21, 2003, seven months after the Federal Aviation Administration (FAA) made the first substantive revision to field approval policy in 20 years
The Question: To field approve or to STC? By Joe Hertzler R ecently I was studying the field approvals of FAA Form 337s, what I consider to be the hottest issue between the FAA and...
In Part 2 of my tome on field approvals, we will cover current field approval policy found in Change 16 to FAA Order 8300.10.
My father was a big man, straight from the old sod. He was a lot smarter than I and a card-carrying survivor of the depression years.